The present invention relates to techniques of identifying a packet and determining a priority order, and to bandwidth control techniques of controlling a bandwidth by queuing a packet in accordance with its priority order, respectively for a packet relay apparatus for relaying a packet in a network. The present invention relates also to techniques of setting priority control information and bandwidth control information for a packet relay apparatus.
A Wide Area Ethernet (registered trademark) network is widely prevailing nowadays, expanding the techniques of Ethernet (registered trademark) used for a local area network (LAN) to a wide area network (WAN). The Tag-VLAN techniques IEEE802.1Q of multiplexing a plurality of virtual LAN's on Ethernet (registered trademark) allow to process each Tag-VLAN as a single user so that a number of users can be accommodated inexpensively and easily.
A quality of service (QoS) control function is known as techniques of preferentially relaying a packet of a particular user in a Wide Area Ethernet (registered trademark) network and controlling a bandwidth. The QoS control function is provided in a packet relay apparatus for relaying a packet, and mainly includes a QoS search unit for identifying a packet and determining a priority order, and a bandwidth control unit for controlling a bandwidth by queuing a packet in accordance with its priority order.
For example, JP-A-2004-363681 describes a method of realizing a QoS control function. With this method, a QoS search unit compares a header of a received packet with the conditions in a search table, and if coincident, the packet is queued in a designated queue. It is necessary to set beforehand conditions to the search table. This method is characterized particularly in that a queuing destination is decided by performing QoS search without restructuring fragment packets divided from one packet to recover the original.
The bandwidth control unit has a hierarchical shaper function described in “AX7800R/AX7700R Software Manual Applications Guide, Vol. 2 Ver. 10.2 compatible” ALAXALA Networks Corporation, June 2006, pp. 36-44. With this hierarchical shaper function described in this Guide, for example, in a network configuration multiplexing VLAN's on one physical port by utilizing a Tag-VLAN function, it is possible to control a bandwidth of each VLAN and control a priority in accordance with user priority order information in a Tag-VLAN header. A minimum bandwidth value, a maximum bandwidth value, a weighting value to be used when a surplus bandwidth is distributed, and the like are set for each VLAN. When the hierarchical shaper function is used, the priority order decision function of the QoS search unit decides aggregate queue information (also called user information) and queue information corresponding to each VLAN to designate a queuing destination of a packet. As this function is applied to downstream traffic of an edge apparatus in a Wide Area Ethernet (registered trademark) network, a minimum bandwidth is ensured for each user even if traffic congestion occurs.
An example requiring the hierarchical shaper function will be described. For example, this function is required if a network to which 500 users belong and a packet relay apparatus are connected by a line of 1 Gbit/s and it is desired to ensure a minimum bandwidth of 1 Mbit/s per user under a line bandwidth contract of 500 Mbit/s. By using the hierarchical shaper function, bandwidth control of two stages can be performed, i.e., the minimum bandwidth of each user is controlled to be 1 Mbit/s while the line is restricted to the contract bandwidth. There are requests to aggregate a plurality of business places into one line by utilizing bandwidth control of three stages such as lines—business places—users in a future network configuration. It is anticipated that the number of hierarchical layers to be subjected to bandwidth control will increase.